Mercurial > dropbear
diff libtommath/bn_mp_reduce_2k_setup.c @ 293:9d110777f345 contrib-blacklist
propagate from branch 'au.asn.ucc.matt.dropbear' (head 7ad1775ed65e75dbece27fe6b65bf1a234db386a)
to branch 'au.asn.ucc.matt.dropbear.contrib.blacklist' (head 1d86a4f0a401cc68c2670d821a2f6366c37af143)
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Fri, 10 Mar 2006 06:31:29 +0000 |
parents | eed26cff980b |
children | 5ff8218bcee9 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/libtommath/bn_mp_reduce_2k_setup.c Fri Mar 10 06:31:29 2006 +0000 @@ -0,0 +1,43 @@ +#include <tommath.h> +#ifdef BN_MP_REDUCE_2K_SETUP_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis + * + * LibTomMath is a library that provides multiple-precision + * integer arithmetic as well as number theoretic functionality. + * + * The library was designed directly after the MPI library by + * Michael Fromberger but has been written from scratch with + * additional optimizations in place. + * + * The library is free for all purposes without any express + * guarantee it works. + * + * Tom St Denis, [email protected], http://math.libtomcrypt.org + */ + +/* determines the setup value */ +int mp_reduce_2k_setup(mp_int *a, mp_digit *d) +{ + int res, p; + mp_int tmp; + + if ((res = mp_init(&tmp)) != MP_OKAY) { + return res; + } + + p = mp_count_bits(a); + if ((res = mp_2expt(&tmp, p)) != MP_OKAY) { + mp_clear(&tmp); + return res; + } + + if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) { + mp_clear(&tmp); + return res; + } + + *d = tmp.dp[0]; + mp_clear(&tmp); + return MP_OKAY; +} +#endif